[Insight-users] inverting a deformation field - problem

[Bradley Lowekamp]

Hello,

It not uncommon for resampling-type algorithms to have some points be mapped out side the the domain. This is why a boundary condition and extrapolators are used. If there are just a limited number of pixel being mapped out side, then the simplest way be by to just check if the pixel is within the image's region.

ITK's registration frameworks solve for a transform which maps from the "Fixed" image to the "Moving" image. This is well described int Chapter Eight of the old Software guide:

http://www.itk.org/ItkSoftwareGuide.pdf

Brad

On Dec 8, 2013, at 6:38 PM, Tim Bhatnagar <tim.bhatnagar at gmail.com> wrote:

> Hello,
> 
> I've created a displacement field via Demons non-rigid registration. I am now trying to create the inverse (using InverseDisplacementFieldImageFilter), but when I am using the indexes to ascribe the inverted field, my program crashes mid-way through, because it appears I am trying to call a negative index (specifically, the 3rd index parameter.. the 'z'-parameter).
> 
> I don't do anything to the displacement field except write it to a vtk file before i invert it.. can anyone suggest a solution? I thought I could try and specify the 'direction' of the field, but I'm not sure where in my pipeline I can set the direction of the inverted displacement field...
> 
> sorry if that's messy.. any thoughts would be appreciated!
> 
> Thanks,
> 
> Tim
> 
> -- 
> Tim Bhatnagar
> PhD Candidate
> Orthopaedic Injury Biomechanics Group
> Department of Mechanical Engineering
> University of British Columbia
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